:root {
  color-scheme: light;
  --page: #f4f7f4;
  --paper: #ffffff;
  --paper-soft: #eaf2ed;
  --ink: #0a2118;
  --muted: #52665d;
  --faint: #71827a;
  --line: #cad8d0;
  --line-strong: #9eb7aa;
  --moss: #0b5c3f;
  --fern: #168b61;
  --signal: #1dba86;
  --mint: #d9fceb;
  --amber: #db9b2b;
  --amber-soft: #fff2cf;
  --blue: #246b92;
  --blue-soft: #dff3ff;
  --shadow: 0 26px 64px rgb(17 55 40 / 12%);
  --header: rgb(244 247 244 / 90%);
  --font-display: "Arial Narrow", "PingFang SC", "Microsoft YaHei", sans-serif;
  --font-body: Inter, "PingFang SC", "Microsoft YaHei", system-ui, sans-serif;
  --font-mono: "SFMono-Regular", Consolas, "Liberation Mono", monospace;
}

[data-theme="dark"] {
  color-scheme: dark;
  --page: #07120e;
  --paper: #0d1e17;
  --paper-soft: #132b21;
  --ink: #e9f6ef;
  --muted: #a7bbb0;
  --faint: #849a8e;
  --line: #244536;
  --line-strong: #3d6a56;
  --moss: #58d9a9;
  --fern: #64e1b0;
  --signal: #78edc0;
  --mint: #163d2e;
  --amber: #f2be58;
  --amber-soft: #3a2e15;
  --blue: #75c8f5;
  --blue-soft: #143248;
  --shadow: 0 30px 80px rgb(0 0 0 / 36%);
  --header: rgb(7 18 14 / 90%);
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
}

body {
  margin: 0;
  background:
    linear-gradient(90deg, color-mix(in srgb, var(--line) 28%, transparent) 1px, transparent 1px) 0 0 / 72px 72px,
    linear-gradient(color-mix(in srgb, var(--line) 22%, transparent) 1px, transparent 1px) 0 0 / 72px 72px,
    var(--page);
  color: var(--ink);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.7;
}

a {
  color: inherit;
  text-decoration: none;
}

button,
input {
  font: inherit;
}

.skip-link {
  position: fixed;
  z-index: 100;
  top: 12px;
  left: 12px;
  padding: 10px 14px;
  border-radius: 8px;
  background: var(--ink);
  color: var(--paper);
  transform: translateY(-180%);
}

.skip-link:focus {
  transform: translateY(0);
}

.site-header {
  position: sticky;
  z-index: 30;
  top: 0;
  border-bottom: 1px solid var(--line);
  background: var(--header);
  backdrop-filter: blur(16px);
}

.header-inner {
  display: flex;
  width: min(1440px, 100%);
  min-height: 68px;
  align-items: center;
  justify-content: space-between;
  gap: 28px;
  margin: 0 auto;
  padding: 0 32px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 11px;
  font-weight: 850;
  letter-spacing: -.02em;
}

.brand-mark {
  position: relative;
  display: block;
  width: 32px;
  height: 22px;
}

.brand-mark span {
  position: absolute;
  top: 3px;
  width: 17px;
  height: 16px;
  border: 3px solid var(--moss);
  border-radius: 999px;
}

.brand-mark span:first-child {
  left: 0;
  border-right-color: transparent;
}

.brand-mark span:last-child {
  right: 0;
  border-left-color: transparent;
}

.header-nav {
  display: flex;
  align-items: center;
  gap: 26px;
  color: var(--muted);
  font-size: 13px;
  font-weight: 700;
}

.header-nav a:hover {
  color: var(--moss);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 10px;
}

.back-link,
.theme-button {
  display: inline-flex;
  min-height: 42px;
  align-items: center;
  justify-content: center;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--paper);
  color: var(--muted);
  font-size: 13px;
  font-weight: 750;
}

.back-link {
  padding: 0 16px;
}

.theme-button {
  min-width: 58px;
  padding: 0 12px;
  cursor: pointer;
}

.back-link:hover,
.theme-button:hover {
  border-color: var(--moss);
  color: var(--moss);
}

.hero {
  display: grid;
  width: min(1440px, 100%);
  grid-template-columns: minmax(0, .82fr) minmax(620px, 1.18fr);
  gap: 58px;
  align-items: center;
  margin: 0 auto;
  padding: 88px 48px 92px;
}

.hero-copy {
  max-width: 590px;
}

.eyebrow,
.section-kicker,
.portrait-heading p {
  margin: 0;
  color: var(--moss);
  font: 800 11px/1.4 var(--font-mono);
  letter-spacing: .16em;
}

.hero h1 {
  margin: 20px 0 24px;
  font-family: var(--font-display);
  font-size: clamp(46px, 6.1vw, 86px);
  font-stretch: condensed;
  font-weight: 900;
  letter-spacing: -.065em;
  line-height: .96;
}

.hero-lead {
  max-width: 560px;
  margin: 0;
  color: var(--muted);
  font-size: 18px;
}

.hero-actions,
.answer-actions,
.license-links {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.hero-actions {
  margin-top: 30px;
}

.button {
  display: inline-flex;
  min-height: 48px;
  align-items: center;
  justify-content: center;
  padding: 0 18px;
  border: 1px solid transparent;
  border-radius: 10px;
  font-size: 14px;
  font-weight: 800;
}

.button-primary {
  border-color: var(--moss);
  background: var(--moss);
  color: #ffffff;
}

.button-primary:hover {
  background: var(--fern);
}

.button-secondary {
  border-color: var(--line-strong);
  background: var(--paper);
  color: var(--ink);
}

.button-secondary:hover {
  border-color: var(--moss);
  color: var(--moss);
}

.source-summary {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 0;
  margin: 42px 0 0;
  border-top: 1px solid var(--line);
}

.source-summary div {
  padding: 18px 14px 0 0;
}

.source-summary div + div {
  padding-left: 18px;
  border-left: 1px solid var(--line);
}

.source-summary dt {
  color: var(--faint);
  font: 700 10px/1.4 var(--font-mono);
  letter-spacing: .08em;
}

.source-summary dd {
  margin: 4px 0 0;
  color: var(--ink);
  font-size: 14px;
  font-weight: 800;
}

.system-portrait {
  position: relative;
  overflow: hidden;
  padding: 26px;
  border: 1px solid var(--line-strong);
  border-radius: 28px;
  background:
    radial-gradient(circle at 24% 0, color-mix(in srgb, var(--signal) 16%, transparent), transparent 34%),
    var(--paper);
  box-shadow: var(--shadow);
}

.system-portrait::before {
  position: absolute;
  top: -80px;
  right: -80px;
  width: 240px;
  height: 240px;
  border: 28px solid color-mix(in srgb, var(--moss) 7%, transparent);
  border-radius: 50%;
  content: "";
}

.portrait-heading {
  position: relative;
  z-index: 1;
  display: flex;
  align-items: start;
  justify-content: space-between;
  gap: 20px;
  padding-bottom: 20px;
  border-bottom: 1px solid var(--line);
}

.portrait-heading h2 {
  margin: 7px 0 0;
  font-size: 20px;
  letter-spacing: -.025em;
}

.portrait-status {
  padding: 5px 9px;
  border: 1px solid var(--line);
  border-radius: 99px;
  color: var(--muted);
  font: 700 10px/1.3 var(--font-mono);
  white-space: nowrap;
}

.stack-map {
  position: relative;
  display: grid;
  grid-template:
    "foundation platform" auto
    "builders platform" auto
    "runtime platform" auto / minmax(0, 1fr) 166px;
  gap: 14px 18px;
  padding: 26px 0 12px;
}

.stack-foundation {
  display: grid;
  grid-area: foundation;
  grid-template-columns: repeat(3, 1fr);
  gap: 8px;
}

.stack-foundation span {
  padding: 8px 10px;
  border: 1px dashed var(--line-strong);
  border-radius: 8px;
  color: var(--muted);
  font: 750 11px/1.4 var(--font-mono);
  text-align: center;
}

.stack-builders {
  position: relative;
  display: grid;
  grid-area: builders;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
}

.stack-builders::before {
  position: absolute;
  z-index: 0;
  top: -15px;
  right: 25%;
  left: 25%;
  height: 15px;
  border-right: 1px solid var(--line-strong);
  border-left: 1px solid var(--line-strong);
  content: "";
}

.stack-builders::after {
  position: absolute;
  z-index: 0;
  right: 25%;
  bottom: -15px;
  left: 25%;
  height: 15px;
  border-right: 1px solid var(--line-strong);
  border-left: 1px solid var(--line-strong);
  content: "";
}

.stack-node,
.stack-runtime,
.stack-platform {
  position: relative;
  z-index: 1;
  display: flex;
  flex-direction: column;
  border: 1px solid var(--line);
  border-radius: 14px;
  background: var(--paper-soft);
}

.stack-node {
  min-height: 126px;
  padding: 17px;
}

.stack-deepagents {
  border-color: color-mix(in srgb, var(--amber) 55%, var(--line));
  background: var(--amber-soft);
}

.stack-langchain {
  border-color: color-mix(in srgb, var(--signal) 55%, var(--line));
  background: var(--mint);
}

.stack-runtime {
  grid-area: runtime;
  align-items: center;
  padding: 15px 18px;
  border-color: color-mix(in srgb, var(--blue) 48%, var(--line));
  background: var(--blue-soft);
  text-align: center;
}

.stack-platform {
  grid-area: platform;
  justify-content: center;
  gap: 11px;
  padding: 20px;
  border-color: var(--moss);
  background: var(--moss);
  color: #ffffff;
}

.stack-node small,
.stack-runtime small,
.stack-platform small {
  margin-bottom: 7px;
  color: currentColor;
  font: 750 9px/1.35 var(--font-mono);
  letter-spacing: .08em;
  opacity: .72;
}

.stack-node strong,
.stack-runtime strong,
.stack-platform strong {
  font-size: 17px;
  letter-spacing: -.02em;
}

.stack-node span,
.stack-runtime span {
  margin-top: auto;
  padding-top: 8px;
  color: var(--muted);
  font-size: 11px;
}

.stack-platform > span {
  padding-bottom: 7px;
  border-bottom: 1px solid rgb(255 255 255 / 22%);
  font: 700 11px/1.4 var(--font-mono);
}

.stack-node:hover,
.stack-runtime:hover {
  border-color: var(--moss);
}

.portrait-note {
  margin: 10px 0 0;
  padding-top: 18px;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 12px;
}

.section {
  width: min(1260px, calc(100% - 48px));
  margin: 0 auto;
  padding: 92px 0;
  border-top: 1px solid var(--line);
}

.section-heading {
  max-width: 760px;
  margin-bottom: 32px;
}

.section-heading h2 {
  margin: 9px 0 12px;
  font-family: var(--font-display);
  font-size: clamp(34px, 4vw, 52px);
  font-weight: 900;
  letter-spacing: -.05em;
  line-height: 1.06;
}

.section-heading > p:last-child,
.split-heading > p {
  margin: 0;
  color: var(--muted);
}

.split-heading {
  display: grid;
  max-width: none;
  grid-template-columns: minmax(0, 1fr) minmax(320px, .7fr);
  gap: 48px;
  align-items: end;
}

.route-selector {
  display: grid;
  grid-template-columns: minmax(300px, .78fr) minmax(0, 1.22fr);
  gap: 18px;
}

.goal-list {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.goal-button {
  display: grid;
  width: 100%;
  min-height: 72px;
  grid-template-columns: 34px 1fr;
  gap: 14px;
  align-items: center;
  padding: 12px 16px;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: var(--paper);
  color: var(--ink);
  text-align: left;
  cursor: pointer;
}

.goal-index {
  display: grid;
  width: 30px;
  height: 30px;
  place-items: center;
  border: 1px solid var(--line);
  border-radius: 50%;
  color: var(--faint);
  font: 750 10px/1 var(--font-mono);
}

.goal-copy strong {
  display: block;
  font-size: 14px;
}

.goal-copy small {
  display: block;
  margin-top: 2px;
  color: var(--muted);
  font-size: 12px;
}

.goal-button:hover,
.goal-button.is-active {
  border-color: var(--moss);
}

.goal-button.is-active {
  background: var(--mint);
}

.goal-button.is-active .goal-index {
  border-color: var(--moss);
  background: var(--moss);
  color: #ffffff;
}

.route-answer {
  position: relative;
  overflow: hidden;
  min-height: 392px;
  padding: 38px;
  border: 1px solid var(--line-strong);
  border-radius: 22px;
  background:
    linear-gradient(135deg, color-mix(in srgb, var(--mint) 72%, var(--paper)), var(--paper) 70%);
}

.route-answer::after {
  position: absolute;
  right: -40px;
  bottom: -50px;
  width: 210px;
  height: 210px;
  border: 22px solid color-mix(in srgb, var(--moss) 10%, transparent);
  border-radius: 50%;
  content: "";
}

.answer-label {
  margin: 0;
  color: var(--moss);
  font: 800 11px/1.4 var(--font-mono);
  letter-spacing: .12em;
}

.answer-module {
  position: relative;
  z-index: 1;
  display: inline-flex;
  margin-top: 28px;
  padding: 7px 11px;
  border: 1px solid var(--moss);
  border-radius: 7px;
  color: var(--moss);
  font: 800 12px/1.4 var(--font-mono);
}

.route-answer h3 {
  position: relative;
  z-index: 1;
  max-width: 650px;
  margin: 18px 0 14px;
  font-size: clamp(28px, 4vw, 44px);
  letter-spacing: -.04em;
  line-height: 1.08;
}

.route-answer > p:not(.answer-label) {
  position: relative;
  z-index: 1;
  max-width: 650px;
  color: var(--muted);
  font-size: 16px;
}

.answer-actions {
  position: relative;
  z-index: 1;
  margin-top: 28px;
}

.text-link {
  display: inline-flex;
  min-height: 48px;
  align-items: center;
  color: var(--moss);
  font-size: 14px;
  font-weight: 800;
  text-decoration: underline;
  text-underline-offset: 5px;
}

.module-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 16px;
}

.module-card {
  position: relative;
  overflow: hidden;
  display: grid;
  min-height: 420px;
  grid-template-rows: auto auto 1fr auto;
  padding: 30px;
  border: 1px solid var(--line);
  border-radius: 20px;
  background: var(--paper);
  scroll-margin-top: 90px;
}

.module-card::before {
  position: absolute;
  top: 0;
  right: 0;
  width: 110px;
  height: 8px;
  background: var(--module-color);
  content: "";
}

.module-card[data-module="langchain"] {
  --module-color: var(--signal);
}

.module-card[data-module="langgraph"] {
  --module-color: var(--blue);
}

.module-card[data-module="deepagents"] {
  --module-color: var(--amber);
}

.module-card[data-module="langsmith"] {
  --module-color: var(--moss);
}

.module-head {
  display: flex;
  align-items: start;
  justify-content: space-between;
  gap: 20px;
}

.module-role {
  margin: 0;
  color: var(--module-color);
  font: 800 11px/1.4 var(--font-mono);
  letter-spacing: .08em;
}

.module-number {
  color: var(--faint);
  font: 700 11px/1.4 var(--font-mono);
}

.module-card h3 {
  margin: 22px 0 8px;
  font-size: 31px;
  letter-spacing: -.04em;
}

.module-tagline {
  margin: 0;
  color: var(--muted);
  font-weight: 750;
}

.module-description {
  margin: 24px 0 0;
  color: var(--muted);
}

.module-outcomes {
  margin: 22px 0 0;
  padding: 18px 0 0;
  border-top: 1px solid var(--line);
  list-style: none;
}

.module-outcomes li {
  position: relative;
  margin: 8px 0;
  padding-left: 19px;
  color: var(--muted);
  font-size: 13px;
}

.module-outcomes li::before {
  position: absolute;
  top: .72em;
  left: 0;
  width: 8px;
  height: 2px;
  background: var(--module-color);
  content: "";
}

.module-action {
  display: inline-flex;
  min-height: 44px;
  align-items: center;
  justify-self: start;
  margin-top: 22px;
  color: var(--module-color);
  font-size: 13px;
  font-weight: 850;
  text-decoration: underline;
  text-underline-offset: 5px;
}

.path-list {
  border-top: 1px solid var(--line-strong);
}

.path-card {
  display: grid;
  grid-template-columns: 140px minmax(250px, .8fr) minmax(360px, 1.2fr) auto;
  gap: 30px;
  align-items: start;
  padding: 28px 0;
  border-bottom: 1px solid var(--line);
}

.path-label {
  color: var(--moss);
  font: 800 11px/1.5 var(--font-mono);
  letter-spacing: .08em;
}

.path-copy h3 {
  margin: 0 0 8px;
  font-size: 22px;
  letter-spacing: -.03em;
}

.path-copy p {
  margin: 0;
  color: var(--muted);
  font-size: 14px;
}

.path-steps {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 8px;
  margin: 0;
  padding: 0;
  counter-reset: path-step;
  list-style: none;
}

.path-steps li {
  position: relative;
  min-height: 48px;
  padding: 12px 12px 12px 38px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--paper);
  color: var(--muted);
  font-size: 12px;
  counter-increment: path-step;
}

.path-steps li::before {
  position: absolute;
  top: 13px;
  left: 12px;
  color: var(--moss);
  font: 800 10px/1.5 var(--font-mono);
  content: counter(path-step, decimal-leading-zero);
}

.path-action {
  display: inline-flex;
  min-height: 44px;
  align-items: center;
  align-self: center;
  padding: 0 14px;
  border: 1px solid var(--moss);
  border-radius: 999px;
  color: var(--moss);
  font-size: 12px;
  font-weight: 850;
  white-space: nowrap;
}

.path-action:hover {
  background: var(--moss);
  color: var(--paper);
}

.source-grid {
  display: grid;
  grid-template-columns: repeat(5, minmax(0, 1fr));
  gap: 10px;
}

.source-card {
  display: flex;
  min-height: 180px;
  flex-direction: column;
  padding: 20px;
  border: 1px solid var(--line);
  border-radius: 14px;
  background: var(--paper);
}

.source-card strong {
  font-size: 15px;
}

.source-card p {
  margin: 10px 0 18px;
  color: var(--muted);
  font-size: 12px;
}

.source-card span {
  margin-top: auto;
  color: var(--moss);
  font: 800 11px/1.4 var(--font-mono);
}

.source-card:hover {
  border-color: var(--moss);
}

.license-panel {
  display: grid;
  grid-template-columns: minmax(260px, .55fr) minmax(320px, .9fr) minmax(260px, .65fr);
  gap: 30px;
  align-items: center;
  margin-top: 16px;
  padding: 28px;
  border: 1px solid var(--line-strong);
  border-radius: 16px;
  background: var(--paper-soft);
}

.license-panel span {
  display: block;
  margin-bottom: 6px;
  color: var(--faint);
  font: 750 10px/1.4 var(--font-mono);
  letter-spacing: .08em;
}

.license-panel code {
  font: 750 12px/1.5 var(--font-mono);
  overflow-wrap: anywhere;
}

.license-panel p {
  margin: 0;
  color: var(--muted);
  font-size: 13px;
}

.license-links {
  justify-content: flex-end;
}

.license-links a {
  color: var(--moss);
  font-size: 12px;
  font-weight: 800;
  text-decoration: underline;
  text-underline-offset: 4px;
}

.page-footer {
  display: flex;
  width: min(1260px, calc(100% - 48px));
  justify-content: space-between;
  gap: 20px;
  margin: 0 auto;
  padding: 34px 0 48px;
  border-top: 1px solid var(--line);
  color: var(--faint);
  font: 700 11px/1.4 var(--font-mono);
}

:where(a, button):focus-visible {
  outline: 3px solid var(--signal);
  outline-offset: 3px;
}

@media (max-width: 1100px) {
  .header-nav {
    display: none;
  }

  .hero {
    grid-template-columns: 1fr;
  }

  .hero-copy {
    max-width: 780px;
  }

  .system-portrait {
    max-width: 820px;
  }

  .source-grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .license-panel {
    grid-template-columns: 1fr 1fr;
  }

  .license-links {
    grid-column: 1 / -1;
    justify-content: flex-start;
  }
}

@media (max-width: 760px) {
  body {
    background-size: 48px 48px;
  }

  .header-inner {
    min-height: 62px;
    padding: 0 16px;
  }

  .brand > span:last-child {
    display: none;
  }

  .back-link {
    padding: 0 12px;
  }

  .hero {
    gap: 44px;
    padding: 58px 20px 64px;
  }

  .hero h1 {
    font-size: clamp(44px, 14vw, 66px);
  }

  .source-summary {
    grid-template-columns: 1fr;
  }

  .source-summary div {
    padding: 13px 0;
  }

  .source-summary div + div {
    padding-left: 0;
    border-top: 1px solid var(--line);
    border-left: 0;
  }

  .system-portrait {
    padding: 18px;
    border-radius: 20px;
  }

  .portrait-heading {
    align-items: start;
    flex-direction: column;
  }

  .stack-map {
    grid-template:
      "foundation" auto
      "builders" auto
      "runtime" auto
      "platform" auto / 1fr;
  }

  .stack-platform {
    display: grid;
    grid-template-columns: 1fr repeat(4, auto);
    align-items: center;
  }

  .stack-platform small {
    grid-column: 1 / -1;
  }

  .stack-platform strong {
    margin-right: auto;
  }

  .stack-platform > span {
    padding: 0 0 0 8px;
    border-bottom: 0;
    border-left: 1px solid rgb(255 255 255 / 22%);
  }

  .section {
    width: min(100% - 36px, 1260px);
    padding: 68px 0;
  }

  .split-heading,
  .route-selector,
  .module-grid,
  .license-panel {
    grid-template-columns: 1fr;
  }

  .split-heading {
    gap: 12px;
  }

  .route-answer {
    min-height: 360px;
    padding: 26px 22px;
  }

  .module-card {
    min-height: 0;
    padding: 24px 20px;
  }

  .path-card {
    grid-template-columns: 1fr;
    gap: 12px;
  }

  .path-steps {
    grid-template-columns: 1fr;
  }

  .source-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .license-links {
    grid-column: auto;
  }

  .page-footer {
    width: min(100% - 36px, 1260px);
    flex-direction: column;
  }
}

@media (max-width: 460px) {
  .header-actions {
    gap: 6px;
  }

  .back-link {
    font-size: 12px;
  }

  .theme-button {
    min-width: 50px;
    font-size: 12px;
  }

  .hero-actions {
    align-items: stretch;
    flex-direction: column;
  }

  .stack-builders {
    grid-template-columns: 1fr;
  }

  .stack-builders::before,
  .stack-builders::after {
    display: none;
  }

  .stack-platform {
    grid-template-columns: repeat(2, 1fr);
  }

  .stack-platform small,
  .stack-platform strong {
    grid-column: 1 / -1;
  }

  .stack-platform > span {
    padding: 6px 0;
    border-top: 1px solid rgb(255 255 255 / 22%);
    border-left: 0;
  }

  .source-grid {
    grid-template-columns: 1fr;
  }

  .source-card {
    min-height: 140px;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }
}